Such tests. Very mocha. Much chai. Amaze!!!

ERHMAGERRRD testing frameworks are so the best. Removed all our custom
code for ensuring test exclusivity and doneness and isolating callbacks
and everything. mocha does it all for us, and makes it pretty.

Also rather than return a long chain of promises that eventually resolve
to truthiness, we now use chai to make assertions about what is good and
right in the world.

Recommended reading:
  https://visionmedia.github.io/mocha
  http://chaijs.com/api/assert/